A method for determining the optimal configuration quantity of frequency converters in open channel pumping stations

Abstract

This invention discloses a method for determining the optimal number of frequency converters (VDCs) for open channel pumping stations. The method includes steps such as obtaining the characteristic curves of the pump units after VDC retrofitting, constructing a pumping station load distribution model for mixed operation of speed-regulating and angle-regulating units, solving for the optimal operation scheme under all operating conditions, calculating the cost payback period of the VDCs, and comprehensively determining the optimal number of VDCs. By employing these steps, the operating efficiency of the pumping station is improved, and the return on investment is optimized, achieving a balance between energy conservation, emission reduction, and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of energy-saving optimization technology for open channel pumping station water diversion projects, and in particular to a method for determining the optimal configuration number of frequency converters in open channel pumping stations. Background Technology

[0002] Water diversion projects are an effective means of alleviating regional water supply and demand imbalances and achieving balanced allocation. As a core component of water diversion projects, the widespread application of pumping stations is driven by the ever-increasing demand for water resources. However, with the increasing operating time of pumping stations year by year, energy consumption has risen significantly, placing a huge energy burden on project operation. Therefore, research on energy conservation, consumption reduction, and economic operation optimization of pumping stations is of significant practical importance.

[0003] In some open channel water diversion projects, large-scale angle-regulating pumping stations often operate at low efficiency due to limitations in water conveyance conditions. Even with optimized scheduling algorithms, the improvement in operating efficiency remains limited. To address this issue, introducing frequency converters (VDCs) into the pumping stations to achieve pump speed regulation is an effective means of improving their performance. However, more complex flow regulation methods not only increase the difficulty of system control but also increase operating and investment costs. Therefore, this invention comprehensively considers the optimization potential of VDC energy saving and proposes a method for determining the optimal configuration number of VDCs in open channel pumping stations, aiming to achieve a balance between energy saving and cost reduction and economic efficiency while improving operating efficiency.

[0004] Currently, no research has yielded a technical method for determining the optimal number of frequency converters in a pumping station. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining the optimal configuration quantity of frequency converters in open channel pumping stations, thereby solving the aforementioned problems existing in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for determining the optimal number of frequency converters in an open channel pumping station includes the following steps.

[0008] S1. Construction of a pump station load distribution model for mixed operation of speed-regulating and angle-adjusting units: Based on the characteristic curves of the pump units after frequency conversion retrofit, the total operating flow rate of the speed-regulating and angle-adjusting units, the number of operating speed-regulating and angle-adjusting units, the number of operating angle-adjusting units, and the speed ratio of the speed-regulating and angle-adjusting units are used as decision variables. With the goal of maximizing the efficiency of the entire pump station, the number of pumps, single-unit flow rate, blade installation angle, and speed variation range are constrained by the pump station operating parameters to construct a pump station load distribution model for mixed operation of speed-regulating and angle-adjusting units.

[0009] S2. Solution of full-condition optimized operation scheme: The optimization algorithm is used to solve the pump station load distribution model of mixed operation of speed-regulating and angle-regulating units and angle-regulating units, so as to obtain the flow optimization distribution scheme under full conditions for engineering scenarios with different number of frequency converters in the pump station, and to quantify the operation effect under each scenario by calculating the proportion of operable operating conditions and the average operating efficiency index of the optimized scheme.

[0010] S3. Calculation of the cost recovery period for frequency converters: Based on the market price of frequency converter equipment cost and the local electricity price, calculate the time to recover the investment in frequency converter equipment under different numbers of frequency converters.

[0011] S4. Determining the optimal number of frequency converters: Based on the percentage of operable operating conditions, average operating efficiency, and cost recovery period, the optimal number of frequency converters for the pump station is determined comprehensively.

[0012] Preferably, step S1 specifically includes the following:

[0013] S11. Select the total operating flow rate Q of the speed-regulating and angle-adjusting generator unit. var Number of operating speed-regulating and angle-regulating units N var Number of angle adjustment units in operation N pow The speed ratio k of the speed-regulating and angle-regulating unit is used as a decision variable;

[0014] Q pow =Q target -Q var

[0015] Among them, Q pow Q represents the total water flow rate of the angle-adjusting unit; target Total water flow rate of the pumping station;

[0016] S12. The optimization objective is to minimize the total power consumption of the pumping station, i.e., maximize the overall efficiency of the pumping station. The overall efficiency of the pumping station is the ratio of the output power to the input power of the pumping unit. Therefore, the objective function is:

[0017]

[0018] Where η is the overall efficiency of the pumping station; n and m are the number of units equipped with frequency converters and the number of units without frequency converters in the pumping station, respectively. and These are the operating flow rate and unit efficiency of the i0th speed-regulating and angle-regulating generator unit, respectively. and The operating flow rate and unit efficiency of the j0th angle-adjusting unit are respectively; ρ is the water density; g is the acceleration due to gravity; H r The water pump unit requires a head;

[0019] The efficiency of a single pump unit is...

[0020] η set =η pump ·η trans ·η motor ·η f

[0021] η motor =F(β)

[0022]

[0023] Where, η set The efficiency of a single pump unit; η pump For pump efficiency; η trans The efficiency of the transmission device; η motor For motor efficiency; η f β is the inverter efficiency; β is the load rate; P out and P N These are the motor's output power and rated power, respectively; q and h are the operating flow rate and head of a single pump unit, respectively.

[0024] S13, The constraints for each decision variable are as follows:

[0025] 0≤Q var ≤Q target

[0026] 0≤N var ≤N var,max

[0027] 0≤N pow ≤N pow,max

[0028] K min ≤K≤K max

[0029] Where, N var,max and N pow,max These represent the total number of speed-regulating and angle-regulating units and the total number of angle-regulating units, respectively; K min and K max These are the minimum and maximum values ​​of the motor speed ratio, respectively.

[0030] The flow rate and blade installation angle constraints for each unit are as follows:

[0031] q min ≤q pow ≤q max

[0032] q min ·K min ≤q var ≤q max ·K max

[0033] α min ≤α≤α max

[0034] Where, q pow and q var These are the single-unit operating flow rates of the angle-adjusting unit and the speed-adjusting angle-adjusting unit, respectively; q min and q max These represent the lower and upper limits of the permissible operating flow rate of the unit before the modification; α is the blade installation angle; α min and α max These are the lower and upper limits of the allowable blade rotation angle, respectively.

[0035] Preferably, in step S2, when calculating the flow optimization allocation scheme under all operating conditions, it is necessary to construct discrete calculation points for the pump station under all operating conditions. The construction method is as follows:

[0036] The operating flow range of discrete pumping stations [Q] min Q max ], thus obtaining the discrete sequence of equal-step flow rates {Q1, Q2, ... Q i-1 Q i};The operating head range of discrete pumping stations [H min H max Its discrete sequence with equal step size is {H1, H2, ... H}. j-1 H j The set of discrete calculation points for the entire operating condition of the pumping station is obtained by combining the flow sequence and the pumping sequence.

[0037] By calculating the percentage of operable operating points and the average operating efficiency index of the optimized scheme, the effectiveness of the optimized scheme under different equipment configurations is quantified.

[0038] Preferably, in step S2, based on data statistical methods, the expansion of the operable operating conditions and the effectiveness of the optimization scheme in improving operating efficiency are quantitatively analyzed compared with those before the frequency converter modification.

[0039] Preferably, step S3 specifically involves calculating the power reduction under different inverter configurations and determining the cost recovery period based on the electricity price standard and inverter investment cost in the area where the project is located.

[0040] The reduced operating power ΔP when the station is equipped with t frequency converters t for,

[0041]

[0042] Where, η t The optimal efficiency of the pumping station is when t frequency converters are installed in the station; η0 is the optimal efficiency of the pumping station before the frequency converter retrofit; Q and H are the flow rate and head of the pumping station, respectively.

[0043] Assume the cost of equipping a single frequency converter is E VFD Therefore, the time required to recover the investment is,

[0044]

[0045] Among them, T t The payback period is the investment payback period when t frequency converters are installed in the station; p is the electricity price.

[0046] Preferably, the procedure before step S1 includes:

[0047] S0. Determination of the characteristic curves of the pump unit after frequency conversion modification: Based on the curve relationship between the pump head, efficiency and shaft power and flow rate under each blade placement angle, the relationship of each curve after frequency conversion modification is derived according to the proportional ratio.

[0048] Preferably, step S0 specifically includes the following:

[0049] S01. Based on the factory characteristic curves of the water pump unit, a quadratic polynomial is used to describe the relationship between the pump's head, efficiency, shaft power, and flow rate at each blade installation angle; the relationship between the curves when the installation angle is θ is...

[0050] H0(q0|θ)=a1q0 2 +b1q0+c1

[0051] η0(q0|θ)=a2q0 2 +b2q0+c2

[0052] P0(q0|θ)=a3q0 2 +b3q0+c3

[0053] Where H0, q0, η0, and P0 are the pump head, flow rate, efficiency, and shaft power at rated speed, respectively; a1, b1, c1, a2, b2, c2, a3, b3, and c3 are the constant coefficients of the corresponding terms.

[0054] S02. Based on the proportional ratio, the relationship between the curves after the frequency converter retrofit is derived as follows:

[0055] H k (q k |θ)=a1q k 2 +b2q k k+c3k 2

[0056] η k (q k |θ)=a2q0 2 +b2q0+c2=η0(q0|θ)

[0057] Pk (q k |θ)=a3q k 2 k+b3q k k 2 +c3k 3

[0058] Among them, H k q k η k P k These represent the pump head, flow rate, efficiency, and shaft power when the speed ratio is k.

[0059] The beneficial effects of this invention are: 1. Solving the problem of low-efficiency operation: This invention improves the operating efficiency of open channel pumping stations and reduces energy consumption by optimizing the configuration of frequency converters. 2. Filling a technological gap: This invention proposes a scientific and reasonable optimal configuration method for frequency converters, making up for the deficiencies in existing research. 3. Optimizing investment costs: This invention avoids blindly implementing full-coverage frequency converter retrofitting, achieving a balance between energy saving and investment costs. 4. Enhancing system control capabilities: This invention reduces the difficulty of complex flow regulation and improves the stability and reliability of pumping station operation. 5. Enhancing energy-saving effects: This invention maximizes the energy-saving benefits of frequency conversion speed regulation, promoting the sustainable development of water resource scheduling systems. Attached Figure Description

[0060] Figure 1 This is a flowchart of the method in an embodiment of the present invention;

[0061] Figure 2 This is a schematic diagram illustrating the construction idea of ​​the flow optimization allocation model under the scenario of 3 generating units (2 equipped with frequency converters) in the station in this embodiment of the invention;

[0062] Figure 3 This is a schematic diagram showing the distribution of operable operating conditions of the Niantou Pumping Station under different configurations of frequency converters in an embodiment of the present invention, where (a), (b), (c), and (d) represent the results when the number of frequency converters is 0, 1, 2, and 3, respectively. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0064] Example 1

[0065] This embodiment provides a method for determining the optimal number of frequency converters in an open channel pumping station to improve pumping station operating efficiency and optimize return on investment. The method first evaluates the impact of frequency converter retrofitting on pump characteristics based on proportional ratio calculations, and then constructs a single-station flow optimization allocation model for speed-regulating and angle-regulating units by combining an equivalent pumping station model and proportional ratios. By calculating full-condition optimized operation schemes under different pump retrofitting numbers, this invention quantifies the impact of different frequency converter retrofitting schemes on the optimization space from two dimensions: expansion of the operable operating range and efficiency improvement. Simultaneously, it calculates the investment payback period by combining electricity price standards and frequency converter market prices, and finally comprehensively evaluates and determines the optimal number of frequency converters in the pumping station, achieving a balance between energy saving and economic benefits. Figure 1 As shown, the method specifically includes the following parts:

[0066] I. Determination of the characteristic curve of the water pump unit after frequency conversion retrofit

[0067] Based on the curves showing the pump's head, efficiency, shaft power, and flow rate at various blade installation angles, the relationships between these curves after frequency conversion modification are derived using a proportional ratio. Specifically, this includes the following:

[0068] 1.1 Based on the factory characteristic curves of the water pump unit, a quadratic polynomial is used to describe the relationship between the pump's head, efficiency, shaft power, and flow rate at each blade installation angle; the relationship for each curve when the installation angle is θ is as follows:

[0069] H0(q0|θ)=a1q0 2 +b1q0+c1

[0070] η0(q0|θ)=a2q0 2 +b2q0+c2

[0071] P0(q0|θ)=a3q0 2 +b3q0+c3

[0072] Where H0, q0, η0, and P0 are the pump head (m), flow rate (m³ / h), and flow rate (m³ / h) at rated speed, respectively. 3 / s), efficiency (%) and shaft power (kW); a1, b1, c1, a2, b2, c2, a3, b3, c3 are the constant coefficients of the corresponding terms;

[0073] 1.2. Based on the proportional ratio, the relationship between the curves after the frequency converter retrofit is derived as follows:

[0074] H k (q k |θ)=a1q k 2 +b2q k k+c3k 2

[0075] ηk (q k |θ)=a2q0 2 +b2q0+c2=η0(q0|θ)

[0076] P k (q k |θ)=a3q k 2 k+b3q k k 2 +c3k 3

[0077] Among them, H k q k η k P k These represent the pump head (m) and flow rate (m³ / h) when the speed ratio is k. 3 / s), efficiency (%) and shaft power (kW).

[0078] II. Construction of a load distribution model for pumping stations operating in combination with speed-regulating and angle-regulating units

[0079] The introduction of frequency converters alters the overall operating characteristics of the angle-adjusting pump units, treating them as two different types of pumps compared to the original angle-adjusting units. Therefore, to simplify the flow optimization solution, pump stations not retrofitted with full frequency converters can be equivalent to a parallel operation system of speed-adjusting and angle-adjusting pump units. Based on this, all pump stations follow the principle of equal flow distribution for unit flow allocation, allowing the optimization model to consider only the total operating flow of each pump station, the number of operating units, and the speed ratio of the speed-adjusting and angle-adjusting pump units, thereby reducing solution complexity and improving computational efficiency.

[0080] The model construction process is as follows: Based on the characteristic curves of the pump units after frequency conversion retrofitting, the total operating flow rate of the speed-regulating and angle-regulating units, the number of operating speed-regulating and angle-regulating units, the number of operating angle-regulating units, and the speed ratio of the speed-regulating and angle-regulating units are used as decision variables. The objective is to maximize the overall efficiency of the pump station. Constraints are placed on the number of pumps, single-unit flow rate, blade installation angle, and speed variation range based on the pump station's operating parameters. This leads to the construction of a pump station load distribution model for the mixed operation of speed-regulating and angle-regulating units and angle-regulating units. Specifically, the model includes the following:

[0081] 2.1 Select the total operating flow rate Q of the speed-regulating and angle-regulating generator unit var Number of operating speed-regulating and angle-regulating units N var Number of angle adjustment units in operation N pow The speed ratio k of the speed-regulating and angle-regulating unit is used as a decision variable;

[0082] Q pow =Q target -Q var

[0083] Among them, Q pow The total water flow rate of the angle-adjusting unit (m³) 3 / s); Q target Total water flow rate of the pumping station (m³) 3 / s).

[0084] 2.2 The optimization objective is to minimize the total power consumption of the pumping station, i.e., maximize the overall efficiency of the pumping station. The overall efficiency of the pumping station is the ratio of the output power to the input power of the pumping unit. Therefore, the objective function for the optimization model of the open channel water conveyance system is:

[0085]

[0086] Where η is the overall efficiency of the pumping station; n and m are the number of units equipped with frequency converters and the number of units without frequency converters in the pumping station, respectively. and The operating flow rates (m³ / s) of the i0th speed-regulating and angle-regulating generator unit are respectively. 3 / s) and device efficiency (%); and The operating flow rates (m³) of the j0th angle-adjusting unit are respectively 3 / s) and device efficiency (%); ρ is the density of water; g is the acceleration due to gravity; H r The water pump unit requires a head.

[0087] The efficiency of a single pump unit is...

[0088] η set =η pump ·η trans ·η motor ·η f

[0089] η motor =F(β)

[0090]

[0091] Where, η set The unit efficiency (%) of a single pump unit; η pump Pump efficiency (%); η trans The efficiency (%) of the transmission device is taken as 1 when the water pump is directly connected to the motor; η motor The motor efficiency (%) can be obtained from the efficiency curve of the motor at the factory; η f The inverter efficiency (%) is taken as a constant value of 0.96 in this embodiment; β is the load rate, and P is the output power of the motor. out and the rated power P of the motor NThe ratio is given in this embodiment, where the motor output power is replaced by the motor shaft power; q and h are the operating flow rates (m³ / s) of a single pump unit, respectively. 3 / s) and head (m);

[0092] 2.3 The constraints for each decision variable are as follows:

[0093] 0≤Q var ≤Q target

[0094] 0≤N var ≤N var,max

[0095] 0≤N pow ≤N pow,max

[0096] K min ≤K≤K max

[0097] Where, N var,max and N pow,max These represent the total number of speed-regulating and angle-regulating units and the total number of angle-regulating units, respectively; K min and K max These are the minimum and maximum values ​​of the motor speed ratio, respectively.

[0098] The flow rate and blade installation angle constraints for each unit are as follows:

[0099] q min ≤q pow ≤q max

[0100] q min ·K min ≤q var ≤q max ·K max

[0101] α min ≤α≤α max

[0102] Where, q pow and q var The single-unit operating flow rates (m³) of the angle-adjusting unit and the speed-adjusting angle-adjusting unit are respectively. 3 / s); q min and q max These represent the lower and upper limits of the permissible operating flow rate of the unit before the modification; α is the blade installation angle (°); α min and α max These are the lower and upper limits of the allowable blade rotation angle, respectively.

[0103] III. Solution of Optimized Operation Scheme under All Operating Conditions

[0104] The particle swarm optimization algorithm is used to solve the load distribution model of the pump station with mixed operation of speed-regulating and angle-regulating units. This allows for the determination of flow optimization distribution schemes under all operating conditions for engineering scenarios with different numbers of frequency converters in the pump station. The operating effect under each scenario is quantified by calculating the proportion of operable operating conditions and the average operating efficiency index of the optimization scheme.

[0105] The operating flow range of discrete pumping stations [Q] min Q max ], thus obtaining the discrete sequence of equal-step flow rates {Q1, Q2, ... Q i-1 Q i};The operating head range of discrete pumping stations [H min H max Its discrete sequence with equal step size is {H1, H2, ... H}. j-1 H j The set of discrete calculation points for the entire operating condition of the pumping station is obtained by combining the flow sequence and the pumping sequence, as shown in Table 1.

[0106] Table 1. Set of All Operating Conditions

[0107] Calculation of operating conditions 1 2 … j-1 j 1 <![CDATA[(Q1,H1)]]> <![CDATA[(Q1,H2)]]> … <![CDATA[(Q1,H j-1 )]]> <![CDATA[(Q1,H j )]]> 2 <![CDATA[(Q2,H1)]]> <![CDATA[(Q2,H2)]]> … <![CDATA[(Q2,H j-1 )]]> <![CDATA[(Q2,H j )]]> … … … … … … i-1 <![CDATA[(Q i-1 ,H1)]]> <![CDATA[(Q i-1 ,H2)]]> … <![CDATA[(Q i-1 ,H j-1 )]]> <![CDATA[(Q i-1 ,H j )]]> i <![CDATA[(Q i ,H1)]]> <![CDATA[(Q i ,H2)]]> … <![CDATA[(Q i ,H j-1 )]]> <![CDATA[(Q i ,H j )]]>

[0108] By calculating the percentage of operable operating points and the average operating efficiency index of the optimized scheme, the effectiveness of the optimized scheme under different equipment configurations was quantified. Furthermore, based on statistical data methods, the expansion of operable operating points and the effectiveness of the optimized scheme in improving operating efficiency were further analyzed compared to before the frequency converter upgrade.

[0109] Particle swarm optimization (PSO) is widely used in solving engineering optimization problems due to its strong search capabilities, good versatility, and fast convergence speed. Although this algorithm is prone to getting trapped in local optima during the solution process, the flow allocation model constructed in this invention has a small number of decision variables, the variables are independent of each other, and there are no nonlinear constraints. Therefore, using this optimization algorithm can obtain an approximate value of the optimal solution within the allowable error range in engineering.

[0110] IV. Calculation of Inverter Cost Payback Period

[0111] Based on the market price of frequency converter equipment costs, and combined with local electricity prices, calculate the payback period for different numbers of frequency converters.

[0112] First, calculate the power reduction under different inverter configurations and then determine the cost recovery period by combining the electricity price standard and inverter investment cost in the project area.

[0113] The reduced operating power ΔP when the station is equipped with t frequency converters t for,

[0114]

[0115] Where, η t The optimal efficiency (%) of the pump station when equipped with t frequency converters; η0 is the optimal efficiency (%) of the pump station before frequency conversion; Q and H are the flow rate and head of the pump station, respectively;

[0116] Assume the cost of equipping a single frequency converter is E VFD If the investment is (in yuan), then the time required to recover the investment is,

[0117]

[0118] Among them, T t The payback period (h) is the investment payback period when t frequency converters are installed in the station; p is the electricity price (yuan / kWh).

[0119] V. Determining the Optimal Number of Frequency Converters

[0120] The optimal number of frequency converters for the pump station is determined by comprehensively considering factors such as the percentage of operable operating conditions, average operating efficiency, and cost recovery period.

[0121] Example 2

[0122] To better illustrate the execution process of this invention, this embodiment uses the Niantou Pumping Station of the Miyun Reservoir Regulation and Storage Project in Beijing as an example to determine the optimal number of frequency converters. The design flow rate of this pumping station is 20m³ / s. 3 / s, configured with 4 water pump units (1 of which is a standby), the single unit flow rate range before frequency conversion retrofit is [4.45, 6.64]m³ / s. 3 The head range is [1.05, 2.45] m. The added frequency converter has an adjustable speed ratio range of 0.7-1. The annual operating period is 9 months, with no water supply in winter, and a daily operating time of 24 hours. The average daily commercial peak-valley electricity price in Beijing is 0.69 yuan / kWh. Based on market research, it is assumed that a set of frequency converter equipment and accessories requires an investment cost of 2.35 million yuan.

[0123] I. Determination of the characteristic curve of the water pump unit after frequency conversion retrofit

[0124] Based on the factory-designed comprehensive characteristic curves of each unit in the embodiment, and using a polynomial to describe the curve relationships under each blade installation angle, the characteristic curves of the pump units after frequency conversion retrofit are further derived and analyzed based on the proportional ratio.

[0125] II. III. Construction of a load distribution model for pump stations operating in combination with speed-regulating and angle-regulating units and the determination of an optimized operation scheme under all operating conditions.

[0126] like Figure 2 and Figure 3As shown, based on the flow optimization allocation model constructed in the invention for the mixed operation of frequency-regulating and angle-regulating units, the optimal allocation scheme under different numbers of frequency converters in the station is obtained. Table 2 shows the flow allocation scheme under some operating conditions. The proportion of operable operating conditions and the average operating efficiency index of the optimized scheme are calculated to quantify the operating effect under each scenario. The results are shown in Tables 3 and 4.

[0127] Table 2 shows the flow distribution schemes for some operating conditions.

[0128]

[0129] Table 3 shows the percentage of operable operating conditions corresponding to different numbers of frequency converters.

[0130]

[0131] Table 4. Average operating point efficiency under different numbers of frequency converters

[0132]

[0133]

[0134] IV. Calculation of Inverter Cost Payback Period

[0135] Based on the average efficiency value in Part 3, the calculation is performed at the pump station design flow rate of 20m³ / h. 3 Table 5 shows the cost recovery time for different numbers of frequency converters in the station under a design head of 2.21m / s.

[0136] Table 5 Cost Recovery Time

[0137]

[0138] V. Determining the Optimal Number of Frequency Converters

[0139] Based on the calculated percentage of operable operating conditions, average operating efficiency, and cost recovery period, and considering economic efficiency, efficiency improvement, and adaptability, configuring two frequency converters for the Niantou pumping station is the optimal choice. This configuration can significantly improve the pumping station's operating efficiency within a shorter investment recovery period, while maximizing operable operating conditions, thereby achieving superior energy-saving effects.

[0140] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are obtained:

[0141] This invention provides a method for determining the optimal configuration number of frequency converters (VDCs) for open channel pumping stations. By optimizing the VDC configuration, this invention improves the operating efficiency of open channel pumping stations and reduces energy consumption. This invention proposes a scientifically sound and reasonable method for optimal VDC configuration, overcoming the shortcomings of existing research. This invention avoids blindly implementing full-coverage VDC retrofits, achieving a balance between energy saving and investment costs. This invention reduces the difficulty of complex flow regulation, improving the stability and reliability of pumping station operation. This invention maximizes the energy-saving benefits of VDC speed regulation, promoting the sustainable development of water resource allocation systems.

[0142] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the optimal number of frequency converters for a canal pump station, characterized in that: Comprising the following steps, S1, the load distribution model of the pump station of the mixed operation of the speed and angle adjusting unit and the angle adjusting unit is constructed: based on the characteristic curve of the water pump unit after the frequency conversion reconstruction, the total running flow of the speed and angle adjusting unit, the running number of the speed and angle adjusting unit, the running number of the angle adjusting unit and the speed ratio of the speed and angle adjusting unit are taken as the decision variables, the highest device efficiency of the whole pump station is taken as the target, the pump quantity, the single machine flow, the blade setting angle and the speed variation range are constrained by the pump station operation parameters, and the load distribution model of the pump station of the mixed operation of the speed and angle adjusting unit and the angle adjusting unit is constructed; S2, the optimal operation scheme under all working conditions is solved: the optimization algorithm is used to solve the load distribution model of the pump station of the mixed operation of the speed and angle adjusting unit and the angle adjusting unit, the flow optimization distribution scheme under all working conditions is solved for the engineering scene of different frequency converter configuration quantities in the pump station, and the running effect under each scene is quantified by calculating the proportion of the running working condition and the average running efficiency index of the optimization scheme; S3, the frequency converter cost investment recovery period is calculated: according to the frequency converter configuration cost of market price, the recovery frequency converter equipment investment time under different frequency converter quantity is calculated combined with the local electricity price; S4, the optimal frequency converter configuration quantity is determined: the optimal frequency converter configuration quantity of the pump station is determined comprehensively according to the proportion of the running working condition, the average running efficiency and the cost recovery period index; Step S1 specifically includes the following contents, S11, selecting the total operating flow of the speed and angle regulator unit , the number of operating units of the speed and angle regulator unit , the number of operating units of the angle regulator unit , the speed ratio of the speed and angle regulator unit as a decision variable; ， wherein, total water delivery flow of the angle adjusting unit; total water delivery flow of the pumping station S12, the lowest total power of the pump station is used as the optimization target, that is, the highest device efficiency of the whole pump station, the device efficiency of the whole pump station is the ratio of the pumping device output power to the input power, and the objective function is, ， wherein, is the device efficiency of the entire pumping station; and are the number of units of the pumping station that are equipped with frequency converters and the number of units that are not equipped with frequency converters, respectively; and are the operating flow rate and the device efficiency of the first unit of the variable speed and variable angle units, respectively; and are the operating flow rate and the device efficiency of the first unit of the variable angle units, respectively; is the water density; is the acceleration due to gravity; is the required head of the water pumping device; The device efficiency of a single pump group is, ， ， ， wherein, is the efficiency of the device for a single pump set; is the efficiency of the water pump; is the efficiency of the transmission; is the efficiency of the electric motor; is the efficiency of the frequency converter; is the load rate; and are the output power and the rated power of the electric motor, respectively; and are the operating flow rate and the head of the single pump set, respectively. S13, the constraint of each decision variable is, ， ， ， ， wherein, and are the total number of speed and angle regulating units and angle regulating units, respectively; and are the minimum and maximum values of the motor speed ratio, respectively. The flow and blade setting angle constraint of each unit is, ， ， ， wherein, and Qr and Qr are the single unit operation flow rates of the governing valve unit and the governing and speed governing valve unit, respectively; and Qmin and Qmax are the lower and upper limits of the allowable flow rate of the unit before the modification, respectively; is the blade setting angle; and are the lower and upper limits of the allowable blade turning angle, respectively.

2. The method for determining the optimal number of frequency converters of the open channel pump station according to claim 1, characterized in that: In step S2, when the flow optimization distribution scheme under all working conditions is solved, the discrete calculation all working condition points of the pump station need to be constructed, and the construction method is, Discrete pump station operable flow interval , obtaining an equi-step flow discrete sequence ; Discrete pump station operating head interval The equal step discrete sequence of which is The pump station discrete calculation full working condition point set is obtained by combining the flow sequence and the head sequence. The effect of the optimization scheme under different equipment configuration is quantified by calculating the proportion of the running working condition point and the average running efficiency index of the optimization scheme.

3. The method for determining the optimal number of frequency converters for a canal pump station according to claim 2, characterized in that: In step S2, based on the data statistical method, the extension of the running working condition compared with before the frequency conversion reconstruction and the effect of the optimization scheme in improving the running efficiency are quantitatively analyzed.

4. The method of claim 2, wherein the method further comprises: determining the optimal number of frequency converters for the open channel pump station based on the calculated number of frequency converters and the calculated number of open channel pump stations. Step S3 is specifically to calculate the power reduction under different frequency converter configuration quantities, and determine the cost recovery period combined with the electricity price standard of the engineering area and the frequency converter investment cost; Station equipment Reduced operating power in the context of a station transducer To, ， wherein, equipped with optimal efficiency of the pump station when the frequency converter is installed; optimal efficiency of the pump station before the frequency conversion is implemented; and respectively the flow rate and the head of the pump station; Suppose the cost of a single VFD is The time required to recover the investment is then, ， Wherein, To equip the station with The investment recovery time length when the station transducer is changed; The electricity price.

5. The method of claim 1 to 4, wherein the method is characterized in that: Before step S1, it also includes S0, the water pump unit characteristic curve after frequency conversion reconstruction is solved: based on the curve relationship of the head, efficiency and shaft power of the water pump under each blade setting angle, the curve relationship after frequency conversion reconstruction is derived according to the proportion rate.

6. The method of claim 5, wherein: Step S0 specifically includes the following contents, S01、According to the characteristic curve of water pump unit, the curve relationship between the head, efficiency and shaft power of water pump and flow rate under each blade setting angle is described by quadratic polynomial. When the setting angle is the curve relationship is ， ， ， wherein, , , , are the water pump head, flow, efficiency and shaft power at rated speed, respectively; , , , , , , , , are the constant coefficients of the respective terms; S02, the curve relationship after frequency conversion reconstruction derived based on the proportion rate is, ， ， ， wherein, , , , are the water pump head, flow rate, efficiency and shaft power, respectively, for a speed ratio of .

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